1. Field of the Invention
The present invention relates generally to a method of manufacturing a multilayered ceramic capacitor by a spin coating process, and a multilayered ceramic capacitor obtained by the above method, and more specifically, to a method of manufacturing a multilayered ceramic capacitor, in which the formation of dielectric layers by spin coating and the formation of inner electrodes thereon are repeatedly performed.
2. Description of the Related Art
A multilayered ceramic capacitor comprises a multilayered ceramic sintered body including a plurality of dielectric layers and inner electrodes formed between the dielectric layers, as illustrated in FIG. 1. In addition, outer electrodes are formed on the sintered body to be electrically connected to the inner electrodes of the sintered body, and also, plated layers are formed on the outer electrodes.
Typically, the dielectric layer in the multilayered ceramic capacitor is prepared by a tape casting process. In the tape casting process, as shown in FIG. 2, a liquid phase ceramic slurry having ceramic powder uniformly dispersed therein is coated on a carrier film through a die, and then dried, to obtain a green sheet. The ceramic slurry for the tape casting process is obtained by mixing the ceramic powder such as BaTiO3, with a solvent, a dispersing agent, and a binder. Various additives may be used to alter the characteristics of the dielectric layer, if necessary.
Thereafter, an inner electrode pattern is printed on the green sheet. For this, a screen printing process is mainly used. The green sheets each of which has the electrode printed thereon are layered to a predetermined number, compressed, cut and then sintered, to manufacture a multilayered ceramic sintered body.
Recently, to develop the ultrahigh capacity multilayered ceramic capacitor, thorough research into thinning the dielectric layer is being conducted. However, limitations are imposed on the formation of thin dielectric layers by the tape casting process. Even if the green sheet is formed to be thin, it is difficult to separate the green sheet from the carrier film. In addition, for the multilayered ceramic capacitor, unevenness due to a step between a surface with inner electrode printed thereon and a surface with no inner electrode printed thereon may cause a pillowing phenomenon.
Thus, a novel method of fabricating the multilayered ceramic capacitor is required, instead of the tape casting process. To satisfy the industrial requirements, extensive and intensive studies have been made, but a desirable solution has not been provided yet.
On the other hand, in techniques for coating a thick ceramic film on a substrate to form a single layer, a spin coating process is used. That is, the sol containing ceramic powder such as PZT (PbZrTiO3) is spin coated at a thickness of 5–20 μm on the substrate, to obtain a PZT film.
In this way, although the spin coating process is used for coating a single layer of thick ceramic film on the substrate, it has not been applied to the fabrication of the multilayered ceramic capacitor to date. This is because it is believed that a process of forming a plurality of dielectric layers on a substrate by spin coating while printing electrodes, to form a bulk body, and then separating the bulk body from the substrate, cannot be achieved.